Circuit control apparatus



, P 22, 1942- J. B. LOONEY 2,296,719

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Patented Sept. 22, 1942 CIRCUIT CONTROL APPARATUS John B. Looney, Birmingham, Ala.

Original application September 30, 1940, Serial No. 359,176. Divided and this application September 9, 1941, Serial No. 410,227

1 Claim. (Cl. 164-68) The present invention is a division of patent application, Serial No. 359,176, filed September 30, 1940, and relates to improvements in circuit control apparatus involving the use of a conventional type of vacuum tube and a relay so connected in circuit therewith that a very small or feeble current can control a comparatively larger strong current. In its more detailed aspects the invention relates to a combination of interrelated mechanisms and circuit arrangements for controlling the feed rolls of a strip feeding device in response to predetermined deflections of a looped portion thereof. The above and further features of the invention will be fully apparent from the following detailed disclosure, the accompanying drawings and the appended claim.

In the drawings:

Figure 1 is a diagrammatic view of coacting instrumentalities and control circuits therefor, illustrating one embodiment of the invention; and

Figure 2 is a similar diagrammatic view illustrating another combination of coacting instrumentalities and circuit control means therefor, embodying the invention.

Referring first to the embodiment of the invention illustrated in Figure l, I and 2 represent the feed wires carrying 110-volt alternating current which excites the primary winding E of a transformer indicated generally at T. The secondary of this transformer includes secondary windings S, S and S A conventional type of vacuum tube V having a filament F, control grid G, screen grid G and plate P has said grid and plate elements so connected to the transformer secondary that there is no flow of current in the plate circuit when the voltage on the grid is zero. The control grid G and screen grid G are connected together by leads 3 and] as shown, thereby increasing the capacity of the grid circuit. Voltage is supplied to the filament F through leads and G and to the plate through leads I and 8, and to the grid through leads 9 and Ill. The circuit is adapted to be automatically closed across the gap II in a manner to be hereafter described. The voltage on the grid is alternating, making it unnecessary to provide a rectifier as customarily required. A relay I2 includes an electromagnetic coil I3 whichis connected by wires 8 and I4 in series with the plate circuit. A condenser I5 is connected across the leads 8 and I4 to stabilize the voltage.

When the circuit is closed at II, a voltage is applied to the grid and thus current flows through the plate circuit. Thus the coil I3 of the relay is energized, thus attracting the armature I6 thereof which is effective to close a circuit across the contacts I1 and I8. The latter are connected to leads Ho and I8a, which arein circuit with the feed wires I and 2, respectively. Connected in series in the circuit Ila and I8a there is an electromagnet I9 which, when the armature I6 closes the circuit across the points I1 and I8, is energized and thus attracts the armature 20 of a defiector member 2| pivoted at 22.

The numeral 23 represents as a whole a mechanism capable of closing the circuit through the leads 9 and I0 across the gap I I. In the embodiment of the invention shown in Figure l, the element 23 takes the form of an ammeter. It is equipped with adjustably mounted contact points 24 and 25, both of which are connected by a lead 9a with the lead 9. A pivotally mounted member 26, corresponding to the pointer of the ammeter, is connected by a lead We with the lead ID, the arrangement being such that when the member 26 strikes either contact 24 or 25, the grid circuit will'be closed across the gap I I. The member 26 may be actuated, for example, by a coil 21 connected in series with a source of current indicated at 28 and with a carbon pile regulator 29, or any other suitable current varying device. As illustrated, the carbon pile or other current regulating device is acted upon by a micrometer caliper which, as diagrammatically shown, includes a bell crank pivoted at 30 and having one portion 3| pressing against the carbon pile and another portion 32' carrying a micrometer caliper roller 33 positioned above an idle backing roller 34. As thus arranged, so long as the gauge or thickness of sheets W carried forward by the conveyor 35 does not vary between predetermined limits, the grid circuit will remain open at the gap II. However, any variation in gauge will be reflected in the movement of the micrometer caliper roller 33 which, in turn, Will vary the pressure on the carbon pile regulator 29, and thus alter the resistance and, therefore, the strength of current flowing through the coil 21. As a result of such current variation, the member 26 will make a contact at 24 when an over-gauge sheet passes the micrometer roller, thus causing current to flow in the plate circuit, whereupon the relay coil I3 will be energized so as to close the grid circuit across contacts I! and I8, and thereby rock the deflector 2|, so that the off-gauge sheet will be guided to the oil-gauge conveyor 36. Similarly, if the sheet is under predetermined gauge, contact will be made by member 26 at the point 25 again energizing the coil I3 and actuating the deflector through the energization of the q coil 13b and attracting the armature 44. closes the circuit across the contacts 45 and d magnet 19. when sheets of normal desired gauge are fed by the conveyor, the deflector 22 remains in the full-line position shown and the sheets carried away on the conveyor 31 to a suitable storage point.

By utilization of the vacuum tube controlled relay described, the relatively heavy current reqfiired to actuate th deflector magnet I9 is controlled to use contacts of a size sufllcient to carry any appreciable amount of current. Utilization of the combination of coacting instrumentalities and circuit connections shown in Figure 1 makes it unnecessary to employ any appreciable strength of current flow through the circuit closing means, since the closing of the circuit in the arrangement illustrated merely applies voltage to the grid of the vacuum tube with a very feeble current flow.

Figure 2 illustrates the invention as applied to means for automatically controlling the amount of slack M in a length of continuous strip 0 which is adapted to be cut by the rotating blades of a flying shear 38. The strip is fed to the shear by spaced pairs of coacting rolls 39 and 40 and the amount of slack M between these spaced pairs of rolls is automatically controlled in a manner to be presently described. Itis necessary to maintain the slack in the strip between the two pairs of rolls 39 and 40 within definite limits in order to insure proper operation of the 'flying shear 38. In this embodiment of the invention, the relays Ba and I3!) illustrated are substantially the same as the relay is of Figure 1 and they are located in substantially the same circuits as shown except that a single transformer suppliespower to both relays. The vacuum tubes V and V are also substantially the same as that shown at V in Figure 1. However, in Figure 2 the lead 3a from the grid circuit is connected by lead 30 with an aluminum roller or other contact device 4| adapted to coact with the strip when the amount of slack M becomes insufllcient. The lead 9 from the secondary winding S of the transformer is connected by a wire 9a with one of the feed rollers 40, or to the housing thereof. A lead 42 in the grid circuit of vacuum tube V is connected by a wire 42a with a block or other contact-making device 43 adapted to'coact with the slack portion of the strip in a manner to be presently described. When the slack or the loop M becomes too great, the strip comes in contact with the block 43, closing the circuit of leads 9 and 42. This energizes the grid circuit and causes a current to flow in the plate circuit of the vacuum tube V thus energizing the relay This of wires 45a and 46a, thus completing a circuit from the feed wires I and 2 through an actuating coil 41.. Energization of the coil 51 shifts the arm 48 of a controller 49 to such position that current supplied to the motor to drives it at a relatively slow speed. The motor is in circuit tion to that imparted by the coil 47.; The coil I 53 is in a circuit including contacts 54 and 58 adapted to be closed by an armature 56 upon energization of the relay coil Ila so as to thus close the circuit via lead wires 54a and 55a to the feed wires I and 2. With the apparatus shown and described, it is apparent that when the slack between the rollers 39 and 40 becomes too small, the strip is pulled up against the roller ll, whereupon the relay I30. is eflective to cause the controller coil to speed up the motor 50 and thus increase the slack. On the other hand, when the slack becomes too great, the circuit is closed through the block 43, thus energizing the other relay l3b, causing the proper controller coil to be energized to slow down the motor 50. Heretofore switches operated mechanically by the rise and fall of the strip have been tried, but they have been found unsatisfactory because they tend to mar the surface of the strip. Electric contacts have also been employed but they have been found objectionable since they have a tendency to burn the strip. By the utilization ofthe combination of elements illustrated and deis desirable to control a relatively large electric current by means of ,a very small or feeble current or with merely a slight variation in voltage potential,

I claim:

In combination, a pair of vacuum tubes, each having a respective filament, grid and plate element, filament, grid and plate feeble current circuits in which said elements are connected, respective relays each having a magnetic coil energized by current flowing in the plate circuit of one of said tubes, respective armatures actuated in response to current fluctuations in said coils, a flying shear, spaced pairs of feed rolls for feeding strip thereto, means for driving said pairs of rolls so as to maintain a slack or looped portion JOHN B. LOONEY. 

